You you what assume means, lol.I assume that garlic is good for ducks in the same way as it is beneficial for us humans. It is a mild natural antibiotic, lowers blood sugar and contains a ton of antioxidants. I gave Limpy duck one garlic capsule per day while he was really miserable.
However, it seems that there are ducks that, like some humans, cannot stand the smell. My duckies reject even mealworms with garlic!
And yes, fresh garlic keeps away those pesky vampires.